From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9915C43381 for ; Thu, 21 Mar 2019 23:10:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DCEA21925 for ; Thu, 21 Mar 2019 23:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727388AbfCUXKu (ORCPT ); Thu, 21 Mar 2019 19:10:50 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:51566 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726529AbfCUXKr (ORCPT ); Thu, 21 Mar 2019 19:10:47 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: gportay) with ESMTPSA id DC14228198C Date: Thu, 21 Mar 2019 19:10:55 -0400 From: =?utf-8?B?R2HDq2w=?= PORTAY To: Matthias Kaehlcke Cc: Mark Rutland , devicetree@vger.kernel.org, Derek Basehore , Heiko Stuebner , linux-pm@vger.kernel.org, Brian Norris , Douglas Anderson , linux-kernel@vger.kernel.org, Chanwoo Choi , Kyungmin Park , Rob Herring , Klaus Goger , MyungJoo Ham , Enric Balletbo i Serra , linux-rockchip@lists.infradead.org, Randy Li , kernel@collabora.com, linux-arm-kernel@lists.infradead.org, Lin Huang Subject: Re: [PATCH v2 3/5] devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A. Message-ID: <20190321231055.j7z23f3k3rcngq4u@archlinux.localdomain> References: <20190319181323.22804-1-gael.portay@collabora.com> <20190319181323.22804-4-gael.portay@collabora.com> <20190320003352.GN112750@google.com> <20190320215013.43zgvyn5frnb3yud@archlinux.localdomain> <20190320220223.GP112750@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190320220223.GP112750@google.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthias, On Wed, Mar 20, 2019 at 03:02:23PM -0700, Matthias Kaehlcke wrote: > Hi Gaël, > > On Wed, Mar 20, 2019 at 05:50:13PM -0400, Gaël PORTAY wrote: > > Hi Matthias, > > > > On Tue, Mar 19, 2019 at 05:33:52PM -0700, Matthias Kaehlcke wrote: > > > ... > > > > @@ -95,6 +103,19 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq, > > > > > > > > mutex_lock(&dmcfreq->lock); > > > > > > > > + if (target_rate >= dmcfreq->odt_dis_freq) > > > > + odt_enable = true; > > > > + > > > > + /* > > > > + * This makes a SMC call to the TF-A to set the DDR PD (power-down) > > > > + * timings and to enable or disable the ODT (on-die termination) > > > > + * resistors. > > > > + */ > > > > + arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0, > > > > + dmcfreq->odt_pd_arg1, > > > > + ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD, > > > > + odt_enable, 0, 0, 0, &res); > > > > > > Is it necessary/desirable to make this call for every frequency > > > change? IIUC it should be only needed when odt_enable changes and the > > > driver could track the state. If the DDR frequency doesn't change too > > > often and the overhead of the call is small it shouldn't be really > > > important though. > > > > > > > I will test your solution first to make sure there is no regression to > > run that call for frequency change only. > Oops, I wanted to say when odt_enable changes since last call. > If there is no frequency change the function returns at the > beginning. My suggestion was to only do the call when 'odt_enable' > changes, i.e. when a change (up or down) passes the 'odt_dis_freq' > threshold. > So, for a reason that I ignore, if we try to save unecessary calls to ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD (odt_enable has not changed since last call), we get stalled in the call to ROCKCHIP_SIP_CONFIG_SET_RAGE that follows. The function arm_smccc_smc never returns and the device hard hang. Thanks to your remark, I have also fixed an issue with the odt_dis_freq value. Its value is initialized to 0 in the probe function. Thus the odt_enable is always true (target_rate > 0). I moved its initialization after the timings are parsed from the device-tree; its value is now none zero (333000000 in my case). > > Also, the call takes around 300us. > > Thanks for the info! > > Matthias > > _______________________________________________ > Linux-rockchip mailing list > Linux-rockchip@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-rockchip Gaël